Implantable flow adjuster
An implantable flow adjuster (20) includes proximal and distal support rings (22, 24) which support a flow adjuster panel (26). The flow adjuster panel (26) divides the lumen through the device (20) into two sections, one of reducing cross sectional area and the other of increasing of increasing cross sectional area. The two sections (40, 42) cause, respectively, an increase in blood pressure and blood flow and a decrease in blood pressure and blood flow. These result is a pressure differential beyond the distal end of the device (20). This pressure differential can be used to divert blood flow away from the neck (14) into an aneurysm (12), thus to reduce pressure and wall sheer stress within the aneurysm in order to assist in the repair of the vessel.
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This application claims the benefit of the filing date of United Kingdom (GB) patent application number 1314488.6, filed Aug. 13, 2013.
TECHNICAL FIELDThe present invention relates to an implantable medical device, in particular for altering the characteristics of blood flow within the vessel of a patient.
BACKGROUND ARTMany factors contribute to the formation of saccular aneurysms, particularly neural aneurysms. One of the major contributors is wall shear stress (WSS), which in addition to hypertension leads to a reduction in the elastic tissue of the tunica media, thereby contributing to the formation of the aneurysm. The effect of wall shear stress is heightened at certain anatomical geometries such as bifurcations.
It is known to try to treat aneurysms by filling the aneurysmal sac with filler such as a prosthetic coil. The methodology behind the use of prosthetic coils is to establish a hard thrombus formation within the sac of the aneurysm as a means of isolating the aneurysm wall from the flow of blood. While this can be effective in the treatment of many types of aneurysm, it is less effective when the aneurysm occurs at a bifurcation or trifurcation, such as at the base of the basilar artery. Furthermore, filling an aneurysm does not necessarily reduce the pressure applied to the wall of the aneurysm sac caused by the blood flow.
It is also known to close off the entrance to the aneurysmal sac or to divert the flow of fluid therefrom, but known devices do not always effectively reduce blood flow into the sac or pressure applied to its wall.
Examples of devices for treating aneurysms can be found in U.S. 2002/0179166, U.S. 2002/0198591, U.S.-2003/0100945, U.S.-2010/0106180 and WO 2012/102919.
SUMMARY OF THE INVENTIONThe present invention seeks to provide improved treatment of aneurysms, in particular an implantable flow adjuster and method of diverting flow from an aneurysm.
According to an aspect of the present invention, there is provided an endoluminal flow adjuster having a diameter, a length delimited by proximal and distal ends, and providing a passage for the flow of fluid therethrough; the flow adjuster including at least one support structure providing proximal and distal supports spaced in a longitudinal direction of the flow adjuster between the proximal and distal ends; and an adjuster element including a panel having a length extending in the longitudinal direction, said panel being disposed between and supported by the proximal and distal supports, the panel dividing the passage through the flow adjuster into first and second parts varying in size over at least a part of the length of the flow adjuster.
Advantageously, the first and second parts provide unequal flow cross sectional areas through the flow adjuster, thereby to create a fluid pressure differential between the first and second parts.
The division of the passage of fluid flow through the lumen of the flow adjuster into uneven paths creates pressure differentials in the vessel, in practice a zone of higher pressure and a zone of lower pressure. This pressure differential can alter the flow path of fluid and in practice to pass across the neck of an aneurysm rather than into the aneurysm. As a result, there is a reduction of blood pressure in the aneurysm and thereby of wall shear stress, which can help in the process of remodelling of the aneurysm and reformation of healthy vessel wall.
Thus, in the preferred embodiment, the first and second parts create two flows of fluid through the flow adjuster, one having a higher fluid pressure relative to the other.
Advantageously, the panel is formed of a sheet of material, which may be substantially impermeable. In some embodiments, the panel has perforations or slots therein, the panel providing a barrier to blood therethrough; that is the slots or perforations are of a size that they do not significantly alter the behaviour of blood passing through the flow adjuster.
The panel is preferably of substantially uniform thickness.
In practice, the panel provides a flow constriction through the flow diverter in one of said first and second parts, the flow constriction varying in transverse cross-sectional area along the length of the panel.
In an embodiment, the panel is transversally curved to provide said first and second flow parts of unequal size. Advantageously, the transverse curvature of the panel varies along the length of the panel.
In another embodiment, the panel extends from a position close to one side of the flow adjuster at the proximal support to a position close to an opposing side of the flow adjuster at the distal support.
In this embodiment, the panel could be a substantially flat structure or could have the curvature mentioned above.
In another embodiment, the panel has a concave or convex shape between the ends thereof. The ends of such a panel may be substantially straight.
Preferably, the proximal and distal supports are ring-shaped. They are advantageously radially compressible. In an embodiment, the proximal and distal supports are stents.
The proximal and distal supports may be made of an elastically deformable material, such as a spring material or a shape memory material.
The proximal and distal supports may be separate from one another, but in other embodiments they are coupled to one another, such as by a wire, tether or tie bar, while in other embodiments they could be part of a single stent structure.
There is also disclosed a method of altering the characteristics of blood flow within the vessel of a patient including the steps of:
deploying in a vessel an endoluminal flow adjuster having a diameter, a length delimited by proximal and distal ends, and providing a passage for the flow of fluid therethrough; the flow adjuster including at least one support structure providing proximal and distal supports spaced in a longitudinal direction of the flow adjuster between the proximal and distal ends; and an adjuster element including a panel having a length extending in the longitudinal direction, said panel being disposed between and supported by the proximal and distal supports, the panel dividing the passage through the flow adjuster into first and second parts varying in size over at least a part of the length of the flow adjuster;
wherein the adjuster element causes blood flow in the vessel to be split into first and second parts having different flow velocities, the flow adjuster being deployed in an orientation in the vessel to create a pressure differential across the vessel at a treatment point of the vessel.
In the preferred embodiment, the method reduces the flow of fluid into an aneurysm sac. In practice, this is achieved by orienting the flow adjuster to create a pressure differential across the width of the vessel at the entrance to the sac, which pressure differential causes blood to flow across the neck of the aneurysm rather than into it. This may, for instance be by ensuring that the pressure differential causes the flow to adjust laterally across the vessel away from the neck of the aneurysm.
Other features are disclosed in the description of the preferred embodiments of the invention which follows. It is to be understood that all such features are applicable to all embodiments disclosed herein.
Embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which:
Described below are various embodiments of flow adjuster for altering the flow of blood within a patient's vessel. The term flow adjuster as used herein encompasses the guiding of the flow of blood within a vessel, in particular to alter the pressure profile across the diameter of the vessel and in the preferred embodiments to create a pressure differential across the width of the vessel at the point of treatment in the vessel, in this example, at the neck of an aneurysm.
The preferred embodiments are described in connection with a flow adjuster intended for implantation in the cerebral vessels. It is to be understood, however, that the teachings herein can be applied in the alteration of the flow in any vessel of a patient. It will be appreciated that the dimensions of the device will differ for different vessel sizes.
Referring to
The devices taught herein are designed to reduce or stop of the flow of blood into the aneurysm by altering the blood pressure at the neck 14 of the aneurysm and consequently reducing the flow of blood into the aneurysm sac 12 itself.
The embodiments of flow adjuster disclosed herein create a pressure differential across the diameter of the vessel 10, preferably just upstream of the neck 14, so as to divert the flow of blood away from the aneurysm. This is achieved by splitting the blood flow in the vessel 10 into at least two portions and subjecting these to different cross-sectional passages, typically one narrowing and the other widening, which generates the desired pressure differential. Beyond the flow adjuster, that is downstream thereof, the pressure of the blood can equalize again, in so doing causing an alteration of the flow of blood across the vessel and in practice away from the aneurysm.
A first embodiment of flow adjuster 20 is shown in
The flow adjuster 20 includes a proximal support 22 which in this embodiment is in the form of a resilient ring of generally circular form. The distal support 22 is located at the distal extremity of the flow adjuster 20. A distal support 24, again being in this embodiment in the form of an annular ring of resilient material, is located at the proximal end of the flow adjuster 20. It is preferred that the proximal and distal supports 22, 24, form the proximal and distal extremities, respectively, of the flow adjuster 20.
Supported by and extending between the proximal and distal supports 22, 24 is an adjuster element 26 which in this example is a substantially rectangular panel made of impermeable or substantially impermeable material and is transversally curved in the longitudinal direction of the flow adjuster 20. More specifically, the panel 26 is in this embodiment attached at diametrically opposite sides 30 of each support 22, 24. The attachment may be by a solder joint, welding, use of bonding agent or any other suitable attachment method. In this embodiment, the panel 26 is attached to the supports 22, 24, such that the proximal edge 32 of the panel 26 is aligned with the proximal edge 34 of the proximal support 22, while the distal edge 36 of the panel 26 is aligned with the distal edge 38 of the distal support 24. In other embodiments, the edges 32, 36 of the panel 26 may be attached at any location within the length, or depth, of the support rings 22, 24.
The proximal and distal supports may be made of a spring material such as spring steel, but are preferably made of a shape memory material, preferably a shape memory alloy such as nickel titanium alloy (Nitinol). In another example they could be made of cobalt chromium. The panel 26 may be made of the same material as the proximal and distal supports 22, 24 but may be made of other materials. These materials and other materials preferably used for the device 20 are anti-thrombotic material.
In the preferred embodiments the device is made of radiopaque materials or includes radiopaque markers. In the preferred embodiment, radiopaque markers or material are provided in the support rings 22, 24.
It will be appreciated that when made of a spring or shape memory material, the device 20 will exhibit resilience, for example compressibility in the radial direction, yet will exert a force tending it to its rest shape, that is its shape when not subjected to an external force. The device can thus be radially compressed in an introducer assembly for delivery and will expand when released from the introducer assembly constraints, in practice until it abuts and presses against the vessel walls as described in detail below. When made of a shape memory material, the device can be manufactured to have a transition temperature around body temperature and thus to exhibit its elastic return force only once deployed in the patient.
The proximal and distal support rings 22, 24 may be continuous rings of strip material or wire. In other embodiments they may have other configurations, such as a split ring, or a conventional stent ring having, for example, a sinusoidal or zigzag shape for radial compressibility. Furthermore, each of the proximal and distal support rings 22, 24 may be made of a single element but could in other embodiments be a set of annular elements, such as turns of a coil, of a strip or the like.
For a device 20 for cerebral applications, the wall thickness of the support elements 22, 24 and of the adjuster element 26 is preferably between about 0.5 mm to about 2.0 mm.
The panel 26 has a curvature which in this embodiment varies along the length of the panel, that is from the distal to the proximal ends of the device. As can be seen in particular in
As will be apparent from
Considering the device 20 in situ in a patient's vessel, the supports 22 and 24 will abut and press against the vessel walls and as a result the vessel wall will provide a tubular lumen through the centre of the device 20. The panel 26 divides that lumen into first and second parts or sections 40, 42, of varying cross-sectional area. If one considers the sections 40 and 42 from the proximal end 22 to the distal end 24, the section 40 has a larger transverse cross-sectional area at the proximal end 22, caused by the concavity of the panel 26 at this point, which then reduces in size towards the distal end 24, where the panel 26 is convex at that side of the device 26. On the other hand, the section or part 42 has a small transverse cross-sectional area at the proximal end 22 which then increases towards the distal end 24. Fluid flowing from the proximal end 22 to the distal end 24 will therefore split with more entering the section 40 than the section 42 due to their size differences. However, as the section 40 reduces in cross-sectional area along the length of the device 26, the flow speed and pressure of the fluid in this side will increase through the length of the device 20. By contrast, a lesser proportion of fluid will enter the device 20 through the section or part 42 but this will reduce in pressure and speed towards the distal end 24 as a result of the increasing cross-sectional area of the part or section 42.
As a result, fluid exiting the device 20 at the distal end 24 will have a relatively high pressure and low flow rate at the exit of section 40, and a relatively low pressure and low flow rate at the exit of section 42. This results in a pressure differential of fluid exiting the device 20 at the distal end 24, in a direction orthogonal to the tangent to the panel 26, in other words orthogonal to the line through the ends 30. This pressure differential causes an alteration in the flow of fluid beyond the device 20, from the high pressure side to the low pressure side. The effect of this in a vessel is shown and described with reference to
With reference to
It will be appreciated that the panel 26 of the embodiment of
Another embodiment of flow adjuster 100 is shown in
The flow adjuster 100 of this embodiment has a structure generally the same as that of the embodiment of
The panel 126 can have similar characteristics to the panel 26 of the embodiment of
The disposition of the panel 126 within the device 100 divides the lumen passing through the device into first and second sections or parts 140, 142, respectively. The first part 140, in this example, has a greater transverse cross sectional area at the proximal end 22 of the device 100, which gradually reduces to the distal end 24 of the device 100. By contrast, the part or section 142 has a smaller cross sectional area at the proximal end 22 of the device 100 and a greater cross sectional area at the distal end of the device. As with the embodiment of
The embodiment of
With reference now to
As with the other embodiments, the panel 226 splits the lumen through the device 200 into first and second sections 240, 242 respectively. In this particular example, the proximal and distal edges 232, 234 of the panel 226 lie along the centreline of the support rings 22, 24 and therefore the proximal and distal ends of the sections 240, 242 have equal cross sectional areas. However, due to the shape of the panel 226, the section 240 will initially narrow and then widen again through the length of the device 200, whereas the section 242 will widen and then narrow through the length of the device. This will cause changes in fluid flow and pressure through the device 200, which assist in generating directional flow of fluid beyond the distal end of the device 200 as in practice passed the neck 14 of an aneurysm 12, as will be apparent from the following description.
Again, the embodiment of
Referring now to
The perforations 330 may in some embodiments be in the form of slits, which in some embodiments may provide no gap in the surface of the panel 326 and therefore no apertures through which blood fluid may pass. This embodiment may perform in a similar manner to the embodiment shown in
As will be apparent from
In other embodiments the support structure 310 can be very similar to that of a conventional stent, that is with sinusoidal or zigzag stent rings coupled by longitudinally extending tie bars.
It will be apparent that in all the embodiments taught herein the supports may be in the form of such a stent structure.
In other embodiments, the proximal and distal support elements could be coupled to one another, for example by appropriate struts or tethers.
It will be appreciated that with the embodiments described above and shown in the Figures, the device will operate the same way whichever way round it is placed in the vessel, subject to its angular orientation in the vessel, as described below.
Referring now to
The flow adjuster creates a pressure change within the flow of fluid at the distal end of the adjuster and in practice at the neck 14 of the aneurysm 12, which acts to divert blood away from the neck 14 of the aneurysm. This has the effect of reducing substantially the amount of blood which enters into the aneurysm. As a result, the substantially reduced flow of blood into the aneurysm 12, allows blood in the aneurysm sac to slow or stagnate, which reduces the wall sheer stress and over time will permit the smooth muscle cells within the tunica media to reform, contributing to the reformation of a healthy vessel without requiring direct treatment of the aneurysm itself.
It will be appreciated that the device has a generally cylindrical shape and can be made available in a range of lengths and diameters to suit a particular patient's anatomy and the vessel to which the device is to be deployed.
Not shown on the drawings are radiopaque markers on the device, which can be used to assist in the correct orientation and placement of the device within the patient. Such radiopaque markers are well known in the art and therefore are not described in detail herein or shown in the drawings.
The panel need not be made of a spring material or shape memory material and in some embodiments could be made of a relatively soft material, even a bioabsorbable material, possibly supported in its configuration by the proximal and distal support elements.
It is to be appreciated that the embodiments of flow adjuster taught herein may be provided with other features commonly found in implantable medical devices, for example anchoring elements in the form of barbs or the like, and retrieval elements such as hooks and the like for withdrawing device from a patient's vessel after completion of a medical procedure. It is envisaged also that the device could be retained permanently within a patient's vessel, not just to treat a formed aneurysm but also in order to prevent the formation of aneurysms or further aneurysms over time.
All optional and preferred features and modifications of the described embodiments and dependent claims are usable in all aspects of the invention taught herein. Furthermore, the individual features of the dependent claims, as well as all optional and preferred features and modifications of the described embodiments are combinable and interchangeable with one another.
Claims
1. A method of altering the characteristics of blood flow within the vessel of a patient including the steps of:
- deploying in a vessel an endoluminal flow adjuster having a diameter, a length delimited by proximal and distal ends, and providing a passage for the flow of fluid therethrough; the flow adjuster including at least one support structure providing proximal and distal supports spaced in a longitudinal direction of the flow adjuster between the proximal and distal ends; and an adjuster element including a panel having a length extending in the longitudinal direction, said panel being disposed between and supported by the proximal and distal supports, the panel dividing the passage through the flow adjuster into first and second parts varying in size over at least a part of the length of the flow adjuster;
- wherein the adjuster element causes blood flow in the vessel to be split into first and second parts having different flow velocities, the flow adjuster being deployed in an orientation in the vessel to create a pressure differential across the vessel at a treatment point of the vessel.
2. A method according to claim 1, including the step of orienting the flow adjuster to create a pressure differential across the width of the vessel at the entrance to the sac.
3. An endoluminal flow adjuster having a diameter, a length delimited by proximal and distal ends, and providing a passage longitudinally through the flow adjuster from the proximal end to the distal end where the proximal and distal ends are open for the flow of fluid through the passage; the flow adjuster including at least one support structure providing proximal and distal supports spaced in a longitudinal direction of the flow adjuster between the proximal and distal ends; and an adjuster element including a panel having a length extending in the longitudinal direction, said panel being disposed between and supported by the proximal and distal supports, the panel dividing the passage through the flow adjuster into first and second parts varying in size over at least a part of the length of the flow adjuster, wherein the passage defines an overall cross-sectional size perpendicular to the longitudinal direction, and the cross-sectional size of the first and second parts of the passage combine to define the overall cross-sectional size of the passage, and a ratio between the cross-sectional size of the first part and the cross-sectional size of the second part varies over at least a part of the length of the flow adjuster, wherein the first part of the passage is open at both the proximal and distal ends and the second part of the passage is open at both the proximal and distal ends such that fluid flow is maintained through both the first part and the second part.
4. An endoluminal flow adjuster according to claim 3, wherein the first and second parts provide unequal flow cross-sectional areas through the flow adjuster, thereby to create a fluid pressure differential between the first and second parts.
5. An endoluminal flow adjuster according to claim 3, wherein the first and second parts create two flows of fluid through the flow adjuster, one having a higher fluid pressure relative to the other.
6. An endoluminal flow adjuster according to claim 3, wherein the first and second parts are of unequal size along at least a portion of the flow adjuster.
7. An endoluminal flow adjuster according to claim 3, wherein the panel is formed of a sheet of material.
8. An endoluminal flow adjuster according to claim 3, wherein the panel is impermeable.
9. An endoluminal flow adjuster according to claim 3, wherein the panel has perforations or slots therein, the panel providing a barrier to blood therethrough.
10. An endoluminal flow adjuster according to claim 3, wherein the panel is of substantially uniform thickness.
11. An endoluminal flow adjuster according to claim 3, wherein the panel provides a flow constriction through the flow diverter in one of said first and second parts.
12. An endoluminal flow adjuster according to claim 11, wherein the flow constriction varies in transverse cross-sectional area along the length of the panel.
13. An endoluminal flow adjuster according to claim 3, wherein the panel is transversally curved to provide said first and second flow parts of unequal size.
14. An endoluminal flow adjuster according to claim 13, wherein the transverse curvature of the panel varies along the length of the panel.
15. An endoluminal flow adjuster according to claim 3, wherein the panel extends from a position close to one side of the flow adjuster at the proximal support to a position close to an opposing side of the flow adjuster at the distal support.
16. An endoluminal flow adjuster according to claim 3, wherein the panel has a concave or convex shape between the ends thereof.
17. An endoluminal flow adjuster according to claim 16, wherein the ends of the panel are substantially straight.
18. An endoluminal flow adjuster according to claim 3, wherein the proximal and distal supports are stents.
19. An endoluminal flow adjuster according to claim 3, wherein the proximal and distal supports are separate from one another.
20. An endoluminal flow adjuster having a diameter, a length delimited by proximal and distal ends, and providing a passage for the flow of fluid therethrough; the flow adjuster including at least one support structure providing proximal and distal supports spaced in a longitudinal direction of the flow adjuster between the proximal and distal ends; and an adjuster element including a panel having a length extending in the longitudinal direction, said panel being disposed between and supported by the proximal and distal supports, the panel dividing the passage through the flow adjuster into first and second parts varying in size over at least a part of the length of the flow adjuster,
- wherein the panel is attached to opposite sides of the proximal support and attached to opposite sides of the distal support, and the panel defines the first and second parts at both the proximal support and the distal support.
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Type: Grant
Filed: Aug 11, 2014
Date of Patent: Dec 19, 2017
Patent Publication Number: 20150051694
Assignee: COOK MEDICAL TECHNOLOGIES LLC (Bloomington, IN)
Inventor: Aidan Furey (Copenhagen)
Primary Examiner: Thomas J Sweet
Application Number: 14/456,160
International Classification: A61F 2/82 (20130101); A61F 2/06 (20130101); A61F 2/91 (20130101);